Free tool
Lug Width Helper
Lug width is the one number you must get right before buying a strap. It is the gap between the lugs where the strap sits, measured in millimeters. Confirm your size below and we will tell you what to measure and where to browse next.
Guidance on how to measure, not a database of specific watch models. Always measure your own watch.
How to find your lug width
- 1 The lug width is the gap between the two lugs, where the strap sits and the spring bar seats. It is not the case diameter.
- 2 Measure across the inside faces of the lugs at the spring bar, in millimeters. Digital calipers are the most accurate; a flat millimeter ruler viewed straight down works for most people.
- 3 If you still have the original strap, the width is often stamped near the lug end. You can also check the watch spec sheet or caseback markings.
- 4 Round to the nearest whole millimeter. Watch straps are sold in whole-mm widths, so your strap must match the gap exactly. Even 1mm off looks wrong or will not seat.
Common widths at a glance
| Width | Notes |
|---|---|
| 18mm | Common on smaller dress watches and some field watches. |
| 19mm | Less common, an odd size. Confirm carefully before ordering, as 19mm straps are harder to find. |
| 20mm | The most common width across dress and sport watches. |
| 21mm | Uncommon. A few sport and dress references use it. Double-check before you buy. |
| 22mm | Very common on dive and tool watches. |
| 24mm | Larger sport, pilot, and oversized cases. |
We do not list lug widths for specific watch models on purpose. The same model can change width across references and production years, so measuring your own watch is the only reliable method. For a deeper walkthrough, read how to measure watch lug width.
How it works
How this tool works
Lug width is the gap between the lugs where the strap's spring bar sits, and it has to match the strap to the millimeter. The helper asks for the number you have and how you got it, because the method decides how much to trust it. Calipers across the inside of the lugs are exact; a ruler is usually right but can read a 19 as a 20; the printed size on an old strap can be wrong if that strap was a compromise; a spec sheet is reliable if it is for the exact reference.
Once you confirm a size, the result tells you what to double-check, such as odd sizes and tapered lugs, and where to browse straps in that width. If you are not sure yet, it walks you through measuring in a minute with what you have on hand.
Reading the result
How to read your result
The confirmed width is the only number a strap listing needs to match. A strap one millimeter too narrow shows an ugly gap and can let the spring bar pop; one too wide will not fit at all.
The what-to-check notes cover the two common traps: watches with 19, 21 or 23 mm odd lugs, where a strap in the nearest even size is a fudge, and straps that taper, where the width at the buckle is a second number that changes how the strap looks.
FAQ
Questions people ask
How do I measure lug width without calipers?+
Lay a millimeter ruler flat across the inside of the lugs where the spring bar sits and read the gap. Hold the watch up to a light so you can see the edges clearly. Repeat once; if you read the same number twice, trust it.
My lug width is 19 mm. Can I use a 20 mm strap?+
Only with a strap that compresses, such as a soft nylon or thin leather, and it will still be a tight fit. A 19 mm strap is the right answer, and more makers carry odd sizes than you would think.
What is a tapered strap?+
A strap that is wider at the lugs than at the buckle, for example 20 to 16 mm. It suits dress watches and smaller wrists. The lug end must still match your watch exactly.
Do spring bars come with the strap?+
Often, but not always, and the ones included can be thin. Keep a set of quality spring bars in the correct width; they are cheap and they are what actually holds the watch on.